P64 Assessment of WRF over the Arabian Gulf using SST data sets ROMS and GFS

Weston, Michael, Marouane Temimi, Naira Chaouch, Jun Zhao, Vineeth Krishnan Valappil, Masdar Institute of Science and technology, United Arab Emirates

We run WRF with two data sets of sea surface temperature (SST) over the Arabian Gulf for case studies between January and March 2016 (i.e. winter). The first data set is the Global Forecast System (GFS) default SST at 0.5 degree (~50 km) spatial resolution and the second data set is from the Regional Ocean Modelling System (ROMS) at 5 km spatial resolution. First we evaluate SST from the two data sets against observations taken at 10 buoys located in the Gulf. Secondly, we evaluate WRF air temperature and water vapour mixing ratio at 2 meters at the same buoy sites. Evaluation shows that the GFS performed better in terms of SST with a mean gross error range of 0.2‑0.8 degrees C (negative and positive mean biases), while the ROMS SST mean gross error range was 0.6‑1.2 degrees C (negative mean bias). However, the 2m air temperature from GFS had a higher error than the ROMS simulation, with mean gross errors of 1.8‑9.3 degrees C (positive bias) and 1.4‑8.9 degrees C respectively (positive bias). The colder SST in ROMS caused a decrease in the 2m air temperature thus bringing the 2m air temperature closer to the observed. For water vapour mixing ratio, GFS performed better with a mean gross error range of 0.002‑0.007 g/kg and ROMS from 0.0025‑0.009 g/kg (positive bias for each). We also present results for tests on the solute effect on evaporation and compare against buoy data and to over land stations to see the extent of the effect of this parameter.